TEM-investigation of CrSiON sample of Lorenzo Castaldi (EMPA)report 3

EMEZ-Proposal 0190

Elisabeth Müller 26.5.2008

Time used:

Microscopy I used your sample as test sample for EDX-mapping for 80h and 50h respectivelyData-analysis/reporting

If any of the TEM-data is used for a publication, I would certainly like to read the publication before submission

I made a test with EDX-mapping and used the CrSiON sample for this. Two of the maps were at lower, one at higher resolution. The former ones for the chemical distibution around two of the big „balls“ and one for the composition modulation.

The times used for the mappings were up to 80 hours measuring time at the Tecnai F30.

Energy (keV)

Co

un

ts

6.04.02.00.0

100

80

60

40

20

0

O

Si

Cr

Cr

Cr

Cr

N

EDX HAADF Detector Area 2

Energy (keV)

Co

un

ts

0.700.600.500.400.30

50

40

30

20

10

0

O

Cr

Cr

CrCr

N

EDX HAADF Detector Area 2

Problem: EDX-mapping on Tecnai F30Windows as defined for the mapping

Problems:

N, Si, O ↔ signal to noise ratio

O ↔ Cr-L lines extremely near

Energy windows as chosen for the EDX-mapping:

N-K: 0.344 - 0.427 eV

O-K: 0.5182 - 0.5358 eV

Si-K: 1.638 – 2.863 eV

Cr-K: 5.257 – 5.578 eV

CrSiON:faults in the layer with big balls (low magnification) and concentration modulation (higher magnification)

Cr-K map N-K map O-K map Si-K map

• small window: used for drift correction• large window: area chosen for the map• ball = Cr-rich area with possibly some Si• area below the ball = Si-rich area

Si-rich

Cr-rich

Very low-magnification EDX-map

Cr-K map N-K map O-K map Si-K map

• small window: used for drift correction• large window: area chosen for the map• size: 256 x 256 pixels = 1532 x 1532 nm• measuring time per pixel: 4“, total time 80h• area per pixel: 6 x 6 nm2

• ball = Cr-rich area with possibly some Si• area below the ball = Si-rich area

Si-rich

Cr-rich

Low-magnification EDX-map

Cr-K map N-K map O-K map Si-K map

• black and white: windows chosen• colored: automatic routine(190 x 190 pixels, 50h)

Energy (keV)

Co

un

ts

0.700.600.500.400.30

50

40

30

20

10

0

O

Cr

Cr

CrCr

N

EDX HAADF Detector Area 2

High-magnification EDX-map• small window: used for drift correction• large window: area chosen for the map• size: 190 x 190 pixels = 236 x 236 nm• measuring time per pixel: 4“, total time 50h• area per pixel: 1.24 x 1.24 nm2

Magnified images of the area marked in the above Cr-map

N-K O-K Si-K_highpass filteredCr-K

O-blue_N-yellow

O-green_Si-rose

Si-turquoise_N-red

• O and N (resp. Cr): maxima and minima just exchanged. Gray areas besides blue lines and between yellow lines contain all three elements: Cr,N,OThe O-N EDX-map nicely confirms the EFTEM result. The main difference is, that the EFTEM result shows a better resolution than the EDX-map, as a slight splitting of the weak blue maximum appears to be split, which is not visble in the EDX-map.

• Si and N (resp. Cr): maxima and minima of the Si is shifted slightly towards sample surface as compared to N and Cr.

Sample surface

• Si and O: maxima of the Si is shifted slightly towards sample substrate as compared to O.

EFTEM

EDX

• Cr and N: maxima and minima at the same positions. Therefore only one of these elements is compared to the others.

elemental distribution

50

70

90

110

130

150

170

190

210

230

250

0 10 20 30 40 50 60 70 80

pixel

inte

nsit

y

Si-K Cr-K

N-K O-K Summary:Concentration maxima • N = Cr (double

maximum with a small minimum in between and separated by a strong minimum)

• O = -N (always one strong maximum followed by a weak one)

• Si: maxima always between the top side of N/Cr-maximum and the bottom side of the O-maximum

top bottom

STEM image acquired during EDX-mapping

HAADF STEM image acquired with small spot size

Cr Cr Cr CrSi Si Si Si